<?php
/**
 * jsmin.php - PHP implementation of Douglas Crockford's JSMin.
 *
 * This is pretty much a direct port of jsmin.c to PHP with just a few
 * PHP-specific performance tweaks. Also, whereas jsmin.c reads from stdin and
 * outputs to stdout, this library accepts a string as input and returns another
 * string as output.
 *
 * PHP 5 or higher is required.
 *
 * Permission is hereby granted to use this version of the library under the
 * same terms as jsmin.c, which has the following license:
 *
 * --
 * Copyright (c) 2002 Douglas Crockford	(www.crockford.com)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * The Software shall be used for Good, not Evil.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 * --
 *
 * @package JSMin
 * @author Ryan Grove <ryan@wonko.com>
 * @copyright 2002 Douglas Crockford <douglas@crockford.com> (jsmin.c)
 * @copyright 2008 Ryan Grove <ryan@wonko.com> (PHP port)
 * @license http://opensource.org/licenses/mit-license.php MIT License
 * @version 1.1.1 (2008-03-02)
 * @link https://github.com/rgrove/jsmin-php/
 */

class JSMin {
	const ORD_LF				= 10;
	const ORD_SPACE			= 32;
	const ACTION_KEEP_A		= 1;
	const ACTION_DELETE_A	= 2;
	const ACTION_DELETE_A_B= 3;

	protected $a			  = '';
	protected $b			  = '';
	protected $input		  = '';
	protected $inputIndex  = 0;
	protected $inputLength = 0;
	protected $lookAhead	  = null;
	protected $output		  = '';

	// -- Public Static Methods --------------------------------------------------

	/**
	 * Minify Javascript
	 *
	 * @uses __construct()
	 * @uses min()
	 * @param string $js Javascript to be minified
	 * @return string
	 */
	public static function minify($js) {
		$jsmin = new JSMin($js);
		return $jsmin->min();
	}

	// -- Public Instance Methods ------------------------------------------------

	/**
	 * Constructor
	 *
	 * @param string $input Javascript to be minified
	 */
	public function __construct($input) {
		$this->input			 = str_replace("\r\n", "\n", $input);
		$this->inputLength = strlen($this->input);
	}

	// -- Protected Instance Methods ---------------------------------------------

	/**
	 * Action -- do something! What to do is determined by the $command argument.
	 *
	 * action treats a string as a single character. Wow!
	 * action recognizes a regular expression if it is preceded by ( or , or =.
	 *
	 * @uses next()
	 * @uses get()
	 * @throws JSMinException If parser errors are found:
	 *				 - Unterminated string literal
	 *				 - Unterminated regular expression set in regex literal
	 *				 - Unterminated regular expression literal
	 * @param int $command One of class constants:
	 *			ACTION_KEEP_A			Output A. Copy B to A. Get the next B.
	 *			ACTION_DELETE_A		Copy B to A. Get the next B. (Delete A).
	 *			ACTION_DELETE_A_B	Get the next B. (Delete B).
	*/
	protected function action($command) {
		switch($command) {
			case self::ACTION_KEEP_A:
				$this->output .= $this->a;

			case self::ACTION_DELETE_A:
				$this->a = $this->b;

				if ($this->a === "'" || $this->a === '"') {
					for (;;) {
						$this->output .= $this->a;
						$this->a			= $this->get();

						if ($this->a === $this->b) {
							break;
						}

						if (ord($this->a) <= self::ORD_LF) {
							throw new JSMinException('Unterminated string literal.');
						}

						if ($this->a === '\\') {
							$this->output .= $this->a;
							$this->a			= $this->get();
						}
					}
				}

			case self::ACTION_DELETE_A_B:
				$this->b = $this->next();

				if ($this->b === '/' && (
						$this->a === '(' || $this->a === ',' || $this->a === '=' ||
						$this->a === ':' || $this->a === '[' || $this->a === '!' ||
						$this->a === '&' || $this->a === '|' || $this->a === '?' ||
						$this->a === '{' || $this->a === '}' || $this->a === ';' ||
						$this->a === "\n" )) {

					$this->output .= $this->a . $this->b;

					for (;;) {
						$this->a = $this->get();

						if ($this->a === '[') {
							/*
								inside a regex [...] set, which MAY contain a '/' itself. Example: mootools Form.Validator near line 460:
									return Form.Validator.getValidator('IsEmpty').test(element) || (/^(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]\.?){0,63}[a-z0-9!#$%&'*+/=?^_`{|}~-]@(?:(?:[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?\.)*[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\])$/i).test(element.get('value'));
							*/
							for (;;) {
								$this->output .= $this->a;
								$this->a = $this->get();

								if ($this->a === ']') {
										break;
								} elseif ($this->a === '\\') {
									$this->output .= $this->a;
									$this->a			 = $this->get();
								} elseif (ord($this->a) <= self::ORD_LF) {
									throw new JSMinException('Unterminated regular expression set in regex literal.');
								}
							}
						} elseif ($this->a === '/') {
							break;
						} elseif ($this->a === '\\') {
							$this->output .= $this->a;
							$this->a			 = $this->get();
						} elseif (ord($this->a) <= self::ORD_LF) {
							throw new JSMinException('Unterminated regular expression literal.');
						}

						$this->output .= $this->a;
					}

					$this->b = $this->next();
				}
		}
	}

	/**
	 * Get next char. Convert ctrl char to space.
	 *
	 * @return string|null
	 */
	protected function get() {
		$c = $this->lookAhead;
		$this->lookAhead = null;

		if ($c === null) {
			if ($this->inputIndex < $this->inputLength) {
				$c = substr($this->input, $this->inputIndex, 1);
				$this->inputIndex += 1;
			} else {
				$c = null;
			}
		}

		if ($c === "\r") {
			return "\n";
		}

		if ($c === null || $c === "\n" || ord($c) >= self::ORD_SPACE) {
			return $c;
		}

		return ' ';
	}

	/**
	 * Is $c a letter, digit, underscore, dollar sign, or non-ASCII character.
	 *
	 * @return bool
	 */
	protected function isAlphaNum($c) {
		return ord($c) > 126 || $c === '\\' || preg_match('/^[\w\$]$/', $c) === 1;
	}

	/**
	 * Perform minification, return result
	 *
	 * @uses action()
	 * @uses isAlphaNum()
	 * @return string
	 */
	protected function min() {
		$this->a = "\n";
		$this->action(self::ACTION_DELETE_A_B);

		while ($this->a !== null) {
			switch ($this->a) {
				case ' ':
					if ($this->isAlphaNum($this->b)) {
						$this->action(self::ACTION_KEEP_A);
					} else {
						$this->action(self::ACTION_DELETE_A);
					}
					break;

				case "\n":
					switch ($this->b) {
						case '{':
						case '[':
						case '(':
						case '+':
						case '-':
							$this->action(self::ACTION_KEEP_A);
							break;

						case ' ':
							$this->action(self::ACTION_DELETE_A_B);
							break;

						default:
							if ($this->isAlphaNum($this->b)) {
								$this->action(self::ACTION_KEEP_A);
							}
							else {
								$this->action(self::ACTION_DELETE_A);
							}
					}
					break;

				default:
					switch ($this->b) {
						case ' ':
							if ($this->isAlphaNum($this->a)) {
								$this->action(self::ACTION_KEEP_A);
								break;
							}

							$this->action(self::ACTION_DELETE_A_B);
							break;

						case "\n":
							switch ($this->a) {
								case '}':
								case ']':
								case ')':
								case '+':
								case '-':
								case '"':
								case "'":
									$this->action(self::ACTION_KEEP_A);
									break;

								default:
									if ($this->isAlphaNum($this->a)) {
										$this->action(self::ACTION_KEEP_A);
									}
									else {
										$this->action(self::ACTION_DELETE_A_B);
									}
							}
							break;

						default:
							$this->action(self::ACTION_KEEP_A);
							break;
					}
			}
		}

		return $this->output;
	}

	/**
	 * Get the next character, skipping over comments. peek() is used to see
	 *	if a '/' is followed by a '/' or '*'.
	 *
	 * @uses get()
	 * @uses peek()
	 * @throws JSMinException On unterminated comment.
	 * @return string
	 */
	protected function next() {
		$c = $this->get();

		if ($c === '/') {
			switch($this->peek()) {
				case '/':
					for (;;) {
						$c = $this->get();

						if (ord($c) <= self::ORD_LF) {
							return $c;
						}
					}

				case '*':
					$this->get();

					for (;;) {
						switch($this->get()) {
							case '*':
								if ($this->peek() === '/') {
									$this->get();
									return ' ';
								}
								break;

							case null:
								throw new JSMinException('Unterminated comment.');
						}
					}

				default:
					return $c;
			}
		}

		return $c;
	}

	/**
	 * Get next char. If is ctrl character, translate to a space or newline.
	 *
	 * @uses get()
	 * @return string|null
	 */
	protected function peek() {
		$this->lookAhead = $this->get();
		return $this->lookAhead;
	}
}

// -- Exceptions ---------------------------------------------------------------
class JSMinException extends Exception {}